Vascular metabolism is closely coupled to the maintenance of force, a function underlying circulatory regulation. The object of this work is to characterize the intermediary metabolism of pulmonary vascular smooth muscle in terms of its respiration and aerobic glycolysis. Polarographic measurements of oxygen consumption and enzymatically determined lactate production will be made in vascular strips under controlled mechanical conditions. Specifically, these metabolic measurements will be correlated with the level of isometric force. The dependence on force will be measured both under conditions when the isomeric force is varied at fixed levels of stimulation by altering the initial tissue length and also at a fixed muscle length at various agonist concentrations. Using this data, the total metabolic rates can be partitioned into tension-dependent and -independent components. The total metabolism and its functional components will be studied with several agonists (K ion, norepinephrine and histamine) as well as under hypoxic conditions. In addition to characterizing the metabolism of this tissue, this information will provide the foundation for understanding the energetics of this muscle. The information obtained in this study on normal pulmonary vascular muscle is essential to the characterization and understanding of pulmonary vascular myopathy.